Typical widespread monitoring, measurement or data collection systems such as Satellite Navigation Augmentation Systems use a number of ground based remote monitoring stations geographically spread over their service area. These stations monitor satellite constellation navigation signals, receiving data enabling them to compute the local time and coordinate of the satellite in a global datum, and provide data to one or more computation centers in charge of determining specific features of the satellite or satellite signals which are monitored. Because of the challenging figures required for data availability, continuity and integrity of service, such systems usually use several computation center working in parallel, but located at different places which may even be distributed over several countries.
As a consequence, it is desirable that the communication between the interconnections in such systems is maintained synchronous and that transit delay is guaranteed, while at the same time communication cost is reduced to a minimum. It is also desired that said operations are performed, without having to rely on a commercial third party worldwide data communication network which may well be of uncertain level of quality of service. Some of the known systems may also have time-critical or even human-safety critical applications such as commercial aeronautical navigation guidance elements or systems.
In addition, some of the existing service Level Agreements commercially available favor different trade-off within their architecture making transit time not a guaranteed feature, unless specially designed for such purpose; or make use of VSAT systems requiring complicated receiving VSAT hubs which finally degrade characteristics of VSAT links.
In order to avoid the above drawbacks, it is desired that data are collected from the numerous remote monitoring stations, widely spread over geographical areas, and are directly made available to several computation centers where such data are processed, with a guaranteed delivery time, preferably similar for all those centers. For some systems like navigation systems, the integrity and time-to-alarm performance are key parameters and conventional solutions available in the commercial telecommunication carrier technology are not considered to be well capable of providing such networking synchronous capability at reasonable costs. Using such systems needed to impose very stringent requirements on terrestrial data communication networks such as guaranteed availability, continuity, bit error rate and transit delay which increase their operating cost and make their design quite complex and sensitive to breaks or outages not very well under control.
Another solution known in the related art is the use of compact earth stations using relatively-small diameter antenna. These stations are known as Very Small Aperture Terminal (VSAT). The solution provided by VSATs enables to avoid landlines but requires multiplexing either at the transmitting or at the receiving side in the architecture. Such multiplexing hub generally requires a ground infrastructure with a larger antenna and also requires the renting of some bandwidth of a commercial satellite communication transponder specifically for the application. Also the conventional VSAT solution usually does not solve the problem of having parallel computers geographically distributed at different locations, having data which are delayed and re-broadcast to other centers, whilst they need to be processed in parallel, since VSAT systems usually require to be coordinated from one location at some point, which becomes a system single-point-of failure and is detrimental to the overall system availability.
Additionally, some applications require end-to-end acknowledgment of data or round-trip delay evaluation which cannot be easily achieved using one-way commercial VSAT systems.
Moreover, new applications are emerging requiring those remote monitoring stations to be located not only on ground, but also spread around oceans or even in orbiting spacecraft.
It is therefore desired to provide a solution for interconnecting elements of a wide area monitoring, measurement or data collection system avoiding final rerouting which could overcome all the above drawbacks.